This invention relates to improved peroxide compositions which, depending upon the constituents of same, may be pourable or sprayable dispersions, powders or the like, and to a process for producing same.
Organic peroxides, primarily benzoyl peroxide, have been employed as catalysts for unsaturated polyester resin syrups, in spray up techniques, molding, mine bolt applications, and the like; in pharmaceutical compositions; and in general, paste applications where the peroxide is also a catalyst, as exemplified by use in reconstruction of automobile bodies. In particular, benzoyl peroxide has been widely utilized, in conjunction with organic plasticizers such as butyl benzyl phthalate or dibutyl phthalate, as catalysts in a "split batch" spray up application of polyester resin syrups. In the split batch process, a first resin syrup includes a catalyst promoter dissolved therein while a second, separate resin syrup has the benzoyl peroxide catalyst dissolved therein. The two resin syrups are independently pumped to the head of a spray gun where they are mixed and sprayed onto the receiving surface, per se, or in conjunction with a reinforcing medium such as chopped glass fibers. More recently, methyl ethyl ketone peroxide has been utilized as a low viscosity, sprayable liquid which obviated the split batch method and replaced same with a single resin syrup pump plus a pressurized catalyst pot. A small catalyst line delivers the methyl ethyl ketone peroxide to the spray head, and represents a much simplified spray up system, though the methyl ethyl ketone peroxide has a bad odor, is toxic, and is flammable.
It is likewise known in the art that the polyester products may be produced as low density foams or high density solid products by the presence or absence of blowing agents in the polymer mix. U.S. Pat. No. 3,224,983 to D'Alello, for example, describes the use of organic carbonates which, when heated, liberate carbon dioxide as a blowing agent for various thermoplastic resins along with a disclosure of lowering of the temperature at which carbon dioxide is liberated by an activator which may be an inorganic acid, base or salt exemplified by sodium carbonate and sodium bicarbonate. In like fashion, U.S. Pat. No. 3,470,114 to Siegel et al., discloses the preparation of foamed unsaturated polyesters wherein carbon dioxide is generated from an aromatic polycarbonate. Foamed unsaturated polyester products are also disclosed in U.S. Pat. Nos. 3,884,844; 3,920,589; 4,028,289; 4,016,112; and 4,119,583.
The prior patented art further discloses stable peroxide dispersions including dispersions of benzoyl peroxide which contain activated gels, including finely divided fumed silicas, exemplified by Cab-o-sil, a silica product manufactured by Cabot Corporation, Boston, Mass. that are activated in the process. The market for fumed silicas (such as Cab-o-sil) is 40-42 million lbs. in the United States and 80-100 million lbs. worldwide (source: U.S. Department of Commerce).
In addition to the above disclosures of the patented prior art, Witco Chemical, U.S. Peroxygen Division, 850 Morton Avenue, Richmond, Calif. 94804 and AKZO Chemical Corporation, Buffalo, N.Y. 14028 manufacture and market commercial suspensions or dispersions of benzoyl peroxide. The particular commercially available suspensions or dispersions of benzoyl peroxide, while analogous to the products of the present invention, are quite distinct from same as will become evident hereinafter. Notably, the Witco and AKZO products possess viscosity limitations not present with the products of the present invention and thus limit the applicability of same. Specifically, viscosity of the presently commercially available products fall in a range of about 2,000 centipoises up, while those of the present invention, as will be specifically described hereinafter, are available at viscosity levels in a range of from about 100 centipoises up. Furthermore, whereas the presently commercially available products are primarily classified by the Department of Transportation as hazardous due to the flammable and explosive nature of same, products according to the present invention are not so classified, and, in fact, in certain forms are not explosive and burn only very slowly. Still further, due to the viscosity limitations of the prior art products, the amount of benzoyl peroxide present in the dispersions has likewise been limited at an upper level somewhere in the neighborhood of 50 to 55 percent by weight, whereas with present products, the concentration of peroxide may be up to about 70 weight percent.
It will thus be readily ascertainable from the following description that products according to the present invention as well as the process for producing same will greatly modify utilization of organic peroxide products. Since the products are not classified as hazardous materials, restrictions will not exist as to the quantity in a single package; the transportation requirements for same; the handling of same in the plant; and the like. Moreover, utilization of products according to the present invention will primarily replace methyl ethyl ketone peroxide catalysts, which are highly toxic, flammable, etc. as catalysts for unsaturated polyester resin syrups. Though the prior art is replete with disclosures of uses to which the present compositions may be employed as well as to the individual disclosed constituents of the compositions, there is no teaching or suggestion in any known prior art as to the present process for production of peroxide dispersions nor to the particular improved products produced thereby.